An American tourist was shot in the back of the head in Mexican waters on Thursday after being ambushed by armed boaters, a Texas sheriff said. It happened near the U.S. boundary of a lake where run-ins with pirates already had fishermen and Texas officials on alert.

Even as rampant drug-related killings continue in Mexico, intensified U.S. efforts to prevent the violence from spilling across the border are succeeding, according to federal data and law enforcement officials.

Even as rampant drug-related killings continue in Mexico, intensified U.S. efforts to prevent the violence from spilling across the border are succeeding, according to federal data and law enforcement officials.

Dozens of people paddled down the Rio Grande in kayaks and canoes Saturday to protest a border fence they say will do little to stop illegal immigration but will destroy the impoverished region's burgeoning bird-watching industry.